[Pw_forum] Applying sawtooth filed parallel to a system

[Mohammed Ghadiyali]

Respected Sir,


Thank you for the detailed information.

I will go through those papers.


Regards,

Ghadiyali Mohammed Kader,

Research Scholar,

Dept. of Physics,

University of Mumbai.


________________________________
From: Thomas Brumme <thomas.brumme at uni-leipzig.de>
Sent: Monday, January 8, 2018 6:26 PM
To: Mohammed Ghadiyali; PWSCF Forum
Subject: Re: [Pw_forum] Applying sawtooth filed parallel to a system


Dear Ghadiyali Mohammed Kader,


the paper by Meyer and Vanderbilt does include a discussion about the "dipole correction".

The whole story (why a dipole correction is needed) is actually a little bit more involved and

not so important - you just need to know, that if you want to simulate a system in an electric

field, you also need to switch on the dipole correction in most cases.


Irrelevant details:


- Neugebauer and Scheffler wanted to simulate the adsorption of Na and K on Ag(111)

  (paper: Phys. Rev. B 46, 16067 (1992))

- to compensate the dipole within the system (to be able to use a 3D-periodic boundary code)

  they introduced an external electric field (the sawtooth potential)

- Bengtsson showed that in this case it is actually not "external" but has an "internal" origin

  and that's why you have to multiply it by a factor of 1/2

  (paper: Phys. Rev. B 59, 12301 (1999))

- the paper by Meyer and Vanderbilt is more or less a summary of these details, i.e., that

  for the internal dipole (also the one induced by the external field) you have a slightly different

  equation (the prefactor and the internal dipole needs to be recalculated each scf step as the

  density changes)

- in VASP they actually don't cite the paper by Bengtsson but only state that a more general

  approach is chosen which does not include the mistake of the Neugebauer/Scheffler paper


Regards


Thomas

On 08.01.2018 13:36, Mohammed Ghadiyali wrote:

Respected Sir,


Thank you for the inputs.

Can you suggest any paper/s where the dipole interaction is explained?

The paper by Meyer and Vanderbilt do not cover it.


Regards,

Ghadiyali Mohammed Kader,

Research Scholar,

Dept. of Physics,

University of Mumbai.


--
Dr. rer. nat. Thomas Brumme
Wilhelm-Ostwald-Institute for Physical and Theoretical Chemistry
Leipzig University
Phillipp-Rosenthal-Strasse 31
04103 Leipzig

Tel:  +49 (0)341 97 36456

email: thomas.brumme at uni-leipzig.de<mailto:thomas.brumme at uni-leipzig.de>

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